The term "peel bond" refers to a structure arranged such that a force tending to separate the bond tends to peel one member from the other, such as peeling the protective layer from a sticky surface.
The term "lap bond" refers to a structure arranged so that the separating force is in shear, i.e. a pull on the members in parallel but opposite directions. This latter bond is far stronger than a peel bond since in a lap bond the separating force is distributed evenly over the entire area of the bond whereas in a peel bond the separating force is at all times concentrated along the bond at the line of junction between the two bonded members.
The term "bond" as employed herein refers to any means of joining materials such as chemical bonding, heat sealing, fusion, gluing, welding, crimping, etc.
A preferred use of the present invention is to provide an easily applied waterproof sleeve about an endless cable. U.S. Pat. No. 3,899,807 to Sovish et al discusses in detail the various prior art approaches to surrounding an endless electrical cable or, more particularly, a splice or joint in such a cable, with a waterproof covering.
In such an environment it is necessary to surround a splice in an electrical cable with a waterproof sleeve. Since such a cable is, for purposes of these considerations, effectively endless it is the usual practice to wrap a loose fitting sheet of heat shrinkable material about the cable and, after applying a device for mechanically holding the edges together shrinking the material so that a tight fitting sleeve is formed about the splice. A loose fitting sleeve is normally used so that access to both of the sheets is available during application of the mechanical device or bonding of the edges if such is to be used.
Numerous different approaches have been employed to achieve the above results with access to only one side of the sheet (wrap). In U.S. Pat. Nos. 3,455,336 and 3,379,218, as examples, a heat recoverable wrap is slit, mechanically joined along specially formed edges, and subsequently shrunk and/or bonded. The resulting structures are expensive and time consuming to fabricate.
The aforesaid U.S. Pat. No. 3,899,807 provided a laminate having layers of material of different heat shrink characteristics to achieve an involute curl. Also the different materials had to be such as to be capable of being bonded to one another. In U.S. Pat. No. 3,542,077, a polymeric material is differentially irradiated so that the main body of a polymeric article is sufficiently cross-linked to be heat shrinkable while portions of the end regions are insufficiently irradiated to be heat shrinkable but are heat sealable; it being well known in the prior art that a polymeric material that is cross-linked so as to be heat shrinkable is not heat sealable and vice versa.